KR20090129329A - Reckoning altimeter and method - Google Patents

Abstract

PURPOSE: A navigation altimeter and a method thereof are provided to measure the forward movement and the altitude change to decide an angle of inclination. CONSTITUTION: A navigation altimeter comprises a speedmeter(32), a front linear acceleration system(34), a DR height computer(40), a yaw rate sensor and a yaw compensator. The speedmeter decides a forward speed. The acceleration system measures the forward acceleration. The DR height computer calculates the altitude change based on the speed and acceleration. The yaw rate sensor measures a yaw rate. The yaw compensator amends the acceleration according to the yaw rate in order to decide the amended acceleration.

Description

Reckoning Altimeter and Method

TECHNICAL FIELD This disclosure relates generally to dead reckoning systems and in particular to dead reckoning altimeter apparatus using a speedometer and forωardlooking accelerometer to measure altitude changes. The present disclosure is also particularly relevant to an inclinometer apparatus using a speedometer and a forward accelerometer for measuring the inclination angle.

Dead reckoning (DR) is the process of measuring a current position based on a previously determined position and preceding that position with the measured velocity, direction and / or acceleration. DR starts with the first known location, or fix. The fix may be determined using ranging, triangulation or map matching. In initiating dead reckoning, it is common to use a radio signal to raise in a Global Navigation Satellite System (GNSS) to set an initial position fix. .

The dead reckoning speed can be measured in many ways. Before using modern instrumentation, a wooden float, called a log, is thrown out of the boat and the buoy passes through the hands of the sailor for the time measured by an hourglass as the boat advances through the water. DR speed was determined by counting knots on the tied line. Many modern merchant ships use engine rpm, an automatic log or bottom detection Doppler sonar, to measure water speed. Road vehicles typically measure their speed by measuring the revolution rates of their wheels. Road vehicles may also use engine rpm and Doppler sonar or Doppler radar for speed measurements. The horizontal direction may be measured with a magnetic gate compass or a flux gate compass. The dead reckoning direction can also be determined by integrating the speed of each change detected by the angular rate sensor. An angular velocity sensor is also called a gyro. An inertial system incorporating directional linear acceleration can be used for dead reckoning, in particular in aircraft.

Despite advances in terms of convenience and accuracy of global navigation satellite systems (GNSS), dead reckoning is still needed when continuous GNSS fixes are not available or noisy. In addition, positioning of global navigation satellite systems tends to be less accurate and more noisy in elevation and vertical heading angles than horizontal position and horizontal heading angles.

In general, the present disclosure relates to an altitude guess navigation system that uses a speedometer and a forward accelerometer to measure altitude changes.

This specification describes an instrument and method for measuring altitude change by measuring forward motion. The present disclosure also describes a mechanism and method for determining the angle of inclination by measuring forward movement.

One embodiment includes a speedometer that determines the forward speed; An accelerometer that measures forward acceleration; And a DR calculator for calculating an altitude change based on the speed and the measured acceleration. The altimeter also includes a yaw rate sensor that measures the yaw angle rate, and a yaw compensator that corrects the acceleration measured according to the yaw rate, and the DR calculator calculates the altitude change. It can be configured to use the corrected acceleration along with the hazard velocity.

Another embodiment is to determine a forward speed; Measuring forward acceleration; And calculating a change in altitude based on the speed and the measured acceleration; and providing a method for dead reckoning altitude. The method also includes measuring the yaw rate, correcting the measured acceleration in accordance with the yaw rate, and using the corrected acceleration along with the speed to calculate the altitude change.

Yet another embodiment includes a speedometer for determining a forward speed; An accelerometer for measuring forward acceleration; And an inclinomemter that includes an incline angle calculator that calculates the inclination angle based on the rate of change and the measured acceleration.The inclinometer also includes a yaw rate sensor that measures the yaw rate and the measured acceleration. An inclination correction device configured to use the yaw rate to correct the tilt angle calculator may be configured to use the corrected acceleration together with the rate of change of velocity to calculate the tilt angle.

Another embodiment is to determine a forward speed; Measuring forward acceleration; And calculating an inclination angle based on the measured acceleration and the rate of change of velocity. The method may also include measuring the yaw rate, correcting the measured acceleration according to the yaw rate, and using the corrected acceleration along with the rate of change of velocity to calculate the tilt angle.

In one embodiment the altitude change is determined based on the forward speed and the forward acceleration.

In one embodiment, the inclination angle is determined based on the rate of change of the forward speed and the rate of forward acceleration.

In one embodiment, the measured acceleration corrects the yaw rate.

In one embodiment, the measured acceleration corrects the yaw rate according to the linear position offset.

In one embodiment the linear position offset is determined based on a return-to-position with positive direction loops.

In one embodiment, the measured acceleration corrects the yaw rate according to the yaw alignment angle.

In one embodiment the yaw alignment angle is determined based on a return-to-position with an opposite direction loop.

In one embodiment, the measured acceleration corrects the accelerometer bias.

In one embodiment, the installation accelerometer bias is determined based on return-to-position with opposite directions.

In one embodiment, the restart accelerometer bias is determined based on the last tilt angle.

In one embodiment the updated accelerometer bias is calibrated based on the difference between the external altitude fix and the dead reckoned altitudes.

The above embodiments of the present invention and other embodiments, and the above attributes and other attributes of the present invention will become apparent to those skilled in the art after reading the following detailed description and viewing the various figures.

The details of the preferred embodiment and the best mode for carrying out the idea of the present invention will be described. It should be understood that it is not necessary to adopt all of the details of the preferred embodiment to implement the idea of the present invention.

1 shows a dead reckoning (DR) altimeter mechanism and inclinometer mechanism, indicated by reference numerals 10 and 12, respectively. The instruments 10, 12 are intended to be transported in a vehicle 14 having a forward movement direction 16 having an unknown inclination angle θ in the horizontal plane 18. The vehicle 14 may be a car, a truck, a train, a trolley, or the like, in which the rear wheels 22 and the front wheels 23 are located on the ground 25.

The instrument 10, 12 includes a speedometer 32 and a forward linear accelerometer 34. The vehicle 14 has a turn radius line R (FIG. 5) passing through a turn center 92 (FIG. 5) of the vehicle 14 and perpendicular to the vehicle 14. In the vehicle 14 turning to the front wheel 23, the turning radius R almost passes through the axle of the rear wheel 22. Accelerometer 34 has a mounting linear position offset L with respect to rotation radius R. As shown in FIG. The linear position offset L is described in the forward direction 16.

The DR altimeter instrument 10 includes a DR altitude calculator 40 (FIG. 2). Inclinometer mechanism 12 includes a tilt angle calculator 42 (FIG. 2). The speedometer 32 may be a speed measuring device or a distance measuring device including a calculating device for calculating the forward speed v (t) based on the distance measured during the known period. Speedometer 32 measures the distance and calculates the speed v (t) in the forward direction 16 based on the number of revolutions of the rear wheel 22 or the front wheel 23 for a period of time. It may be an odometer. Alternatively, the speedometer 32 may measure the forward speed v (t) of the vehicle 14 with the Doppler radar or Doppler sonar or optics measuring from the signal reflected from the ground 25. For example, an airplane may use instruments 10, 12 with speedometers 32 that calculate speed v (t) based on Doppler. The accelerometer 34 may be a single axis device mounted to measure the acceleration α _m (t) in the forward direction 16, using a linear combination of two or three axis linear accelerometers. It may also be a two or three axis device for measuring the acceleration (α _m (t)) of the forward direction (16).

FIG. 1A shows the physical mounting of an accelerometer 34 having a measuring direction 46 with a yaw alignment angle γ relative to the forward direction 16 of the vehicle 14. In the simple case the measurement direction 46 is the same as the advance direction 16. However, the sensor for the accelerometer 34 may be mounted such that the measuring direction 46 differs from the forward direction 16 by the yaw alignment angle γ in the horizontal plane.

2 is a block diagram of the dead reckoning altitude mechanism 10 and the inclinometer mechanism 12 having the DR altitude calculator 40 and the inclination angle calculator 42. The instrument 10, 12 includes an acceleration correction device 50 and a yaw rate sensor 52. The yaw rate sensor 52 measures the yaw rate (ω (t)). The acceleration compensator 50 measures the measured acceleration α _m (t) on the influence of the yaw rate (ω (t)) and the influence of the accelerometer bias β to determine the corrected acceleration α _c (t). )).

The DR altitude calculator 40 uses the forward speed v (t) and the corrected forward acceleration α _c (t) to calculate the altitude change ΔH. The tilt angle calculator 42 includes a speed rate calculator 55 that uses the speed v (t) to determine the rate of change of velocity Δv / Δt over time and to calculate the tilt angle θ. The velocity ratio Δv / Δt is used together with the corrected forward acceleration α _c (t).

3 is a functional block diagram of the acceleration correction device 50. The acceleration compensator 50 includes a yaw compensator 62 including a yaw distance compensator 64 and a yaw alignment compensator 66. The yaw distance correction device 64 measures the yaw velocity (ω (t) to calculate a position offset acceleration measurement error that occurs when the vehicle 14 rotates (yawing). ) And offset L, and correct this error to the measured acceleration a _m (t). The position offset error is calculated as ω ² (t) × L. To calculate the yaw alignment angle acceleration measurement error that occurs when the vehicle 14 rotates (yawing), the yaw alignment corrector 66 measures the measured yaw velocity (ω). (t)), velocity v (t) and yaw alignment angle γ are used to correct this error for the measured acceleration α _m (t). The yaw alignment angle error is calculated as ω (t) × v (t) × γ.

Acceleration compensator 50 also includes a return-to-position compensation detector 72, a restart bias detector 74 and an accelerometer bias compensator 76. Include.

The calibration detector 72 tracks the change in altitude (ΔH) between triggers, so that the sum of the change in altitude (ΔH) between the triggers is zero, or the return altitude (H _R ) is the starting altitude (H _1). Determine the installation accelerometer bias (β _I ) so that In order to eliminate the effect of the parking position pitch angle, the vehicle 14 may be parked in the opposite direction to determine the altitude H _R and H ₁ . An accelerometer bias β _I due to an altitude change ΔH ′s of which the sum is zero is determined. The trigger can be automated (preferably after manual enablement) when the instruments 10, 12 detect that the horizontal position has returned, or when the operator has manually returned to the same position. In order to determine the combination of accelerometer bias (β _I ), linear position offset (L) and yaw alignment angle (γ), the vehicle 14 re-turns to the starting position at least once in a clockwise loop and at least once in a counterclockwise direction. driven to loop back. This operation is shown in the flowcharts of FIGS. 8 and 7B and 7C and described in the accompanying detailed description.

The restart bias detector 74 has the idea that the speed v (t) when the vehicle 14 starts to move is still almost zero, and that the inclination angle θ when it starts to move is the last just before the vehicle 14 stops. Use the idea that it is approximately equal to the inclination angle θ _L. Therefore, the restart accelerometer bias β ₀ is calculated by equation (1). In the equation 1, the acceleration α is preferably taken after the acceleration is corrected by the yaw rate ω (t). g is the gravitational acceleration constant.

Equation 1) β ₀ = α-g sinθ _L

The accelerometer bias β may change rapidly when the instrument 10, 12 warms up after the power is turned off. The warm-up time will be long before the accelerometer bias β is stable enough to be accurately calibrated. Moving the tilt angle speed when (θ _L) starts to assume and to move the stop not changed in the tilt angle (θ _L) calculated in the last the last time it was moved immediately before at the beginning (v (t)) is restarted under the assumption that 0 accelerometer The bias β ₀ can be determined to alleviate this problem according to equation (1).

The accelerometer bias compensator 76 compares the installation bias β _I and / or the restart bias β ₀ and / or external navigation information to correct the measured acceleration α _m (t). ). A Kalman filter 80 (FIG. 4) may be included as part of the accelerometer bias corrector 76 to better continuously measure the bias β. When the Kalman filter obtains a new calibration, the bias compensator 76 switches a bias switch to switch between the installation accelerometer bias (β _I ), the restart accelerometer bias (β ₀ ), and the newly calibrated accelerometer bias (β). It may also include.

Accelerometer (34) to change the acceleration (α _m (t)) measurement by a near-constant gravity bias term of g × sin (vertical misalignment angle). The small vertical misalignment angle of) acts on the gravitational acceleration (g). This gravity bias term effectively adds (or subtracts) the determined and corrected accelerometer bias β.

4 is a block diagram of the instrument 10, 12 having a Kalman filter 80 and one or more external positioning sources 82. Exemplary external sources 82 include, but are not limited to, global navigation satellite system (GNSS) receivers 84, baroaltimeters 85, and map matchers 86. The GNSS receiver 84 is a three-dimensional position including time, three-dimensional velocity, tilt angle, satellite signal Doppler (GNSS-based external altitude fix (H _EXT )). GNSS signals are received and processed to provide GNSS-based positioning information, such as satellite signal Dopplers, satellite pseudoranges, and the like. Barometric altimeter 85 provides an air pressure based external altitude fix (H _EXT ). The map matcher 86 provides a GNSS receiver (GNSS receiver) to align the position on the road or track with a line on the electronic map and to adjust the position of the road or track according to direction heading information. Position and orientation from 84, or the output of the Kalman filter 80. The map matcher 86 then provides a map that best fits the location along the road or track or line. Position according to the road, track or line may have a map (map based altitude) based on the height (H _EXT) as a topographic map (topographic map) that may be used by the Kalman filter 80.

The speedometer 32, the accelerometer 34, and the yaw rate sensor 52 have a velocity v (t), a measured acceleration α _m (t), and a yaw rate ω (t) on the Kalman filter 80. To provide). The Kalman filter 80 filters the difference between the noise at the input and / or the discrete external altitude position (H _EXT 's) and the estimated navigation altitude (H's) at the output, and the estimated navigation altitude (H) is the altitude change ( Is determined by accumulating ΔH). The filtered difference is used in the feedback loop to provide a corrected version of the accelerometer bias β. The Kalman filter 80 may be stored in a tangible medium as computer-readable instructions for instructing a computer device, such as the instrument 10, 12, etc. to carry out the instructions.

Acceleration bias β, altitude change ΔH's, speed v (t) (or speed v (t)) of speedometer 32 (or distance at speedometer 32 from which ΔS / Δt can be calculated) ΔS)), measured forward acceleration α _m (t) (or some corrected acceleration or fully corrected acceleration α _c (t)), and external sources including but not limited to external altitude H _EXT The filter 80 utilizes any available information, including but not limited to the positioning navigation information of (82). The Kalman filter 80 uses this information to calculate a three dimensional direction including a three dimensional position including altitude H, a three dimensional velocity and an inclination angle [theta].

The Kalman filter 80 utilizes several, continuous and accurate several navigation inputs to continuously measure and update the 3D direction, 3D position and 3D speed. Navigation inputs include barometric pressure, GNSS satellite pseudoranges, map matching for Doppler, latitude, longgitude, and external altitude (H _EXT ) at GNSS receiver 84, for orientation Yaw rate sensor 52, which may be a gyro for map matching, yaw rate (ω (t)), velocity (v (t)) or distance (S) measurements from speedometer 32 and accelerometer 34 Includes, but is not limited to, a forward acceleration α _m (t) measured value. The GNSS receiver 84 may be a global positioning system (GPS) receiver.

Internal or hidden actuation of the Kalman filter 80 corrects the measured acceleration α _m (t) and corrects the accelerometer bias β used to correct and / or smooth the direction, position and velocity output. To provide. Kalman filter 80 is described in US Pat. No. 5,416,712 to Geier et al. Entitled "position and velocity estimation system for adaptive weighting of GPS and dead reckoning information." Operates in a similar manner to the Kalman filter, which is incorporated herein by reference. To better understand the filtering techniques of the Kalman filter 80, ISBN 1-1-58053-894-0, Copyright 2006, Massachusetts, Norwood, second edition, published by Arttech House, Elliot Kaplan and Christopher By Hegarty, "Understanding GPS: Theory and Application." Particularly beneficial is Section 9.3 on sensor integration in land vehicles such as Geier.

FIG. 5 shows the position offset L in the forward direction 16 between the accelerometer 34 and the radius of rotation R perpendicular to the vehicle 14 passing through the center of rotation 92 of the vehicle 14. . In the vehicle 14 using the front wheel 23 for rotation, the rotation radius R almost passes through the axle of the rear wheel 22. The yaw alignment angle γ is an angle between the forward direction 46 of the accelerometer 34 and the forward direction 16 of the vehicle 14.

6 is a flowchart for determining the altitude change ΔH and the inclination angle θ. The steps of the method may be stored in the fluid medium 100 in a computer-readable form that can be read by a computer to perform the steps. The instruments 10, 12 may be functioned, operated and operated by a computer to be executed at this stage. In step 102 the acceleration α _m (t) is measured. In step 104 the speed v (t) is determined. In step 106 the yaw rate ω (t) is measured. In step 110 and 112 the influence of the rate ω (t) is corrected on the acceleration α _m (t). In step 110 the linear position offset L is corrected for acceleration as a function of the yaw rate ω (t). In step 112, the yaw alignment angle γ is corrected for acceleration as a function of the yaw rate ω (t) and the speed v (t). In step 114 the accelerometer bias β is corrected for acceleration. In the installation correction, the accelerometer bias β may be determined from the return to position method (FIG. 8) as the accelerometer bias β _I. Upon restart, the accelerometer bias β may be calculated at the last tilt angle θ _L as the accelerometer bias β ₀ (FIG. 7A).

In step 116 the altitude change ΔH is calculated from the speed v (t) and the corrected acceleration α _c (t). In step 118 external positioning information, such as position, pseudoranges, altitude, Doppler and direction, is received at the external positioning source 82. In step 122 an altitude change ΔH is accumulated to provide a DR altitude H. For continuous operation, the DR altimeter 10 accumulates a series of altitude changes ΔH's at the last previous DR altitude H to provide a continuous sequence of DR altitudes H's. In step 124 the DR altitude (H) based on external positioning information using Kalman filtering technique to calculate the three-dimensional position including altitude (H), three-dimensional velocity and three-dimensional direction including tilt angle (θ). Filter Accelerometer bias with Kalman filtering technique using external positioning information applied to update the accelerometer bias β used to provide the DR altitude H and the corrected acceleration α _c (t) in step 126. Recalibrate (β). Steps 124 and 126 are generally implemented with state-of-the-art Kalman filtering techniques.

In step 132, the rate of change of velocity Δv / Δt is calculated from the velocity v (t) and time. In step 134, the tilt angle θ is calculated from the corrected acceleration α _c (t) and the rate of change Δv / Δt using Equation 4 below.

7A is a flow chart of a method for calculating the restart accelerometer bias β ₀ . The steps of the method may be stored in a tangible medium 150 in a computer-readable form that can be read by a computer for performing the steps. The instruments 10, 12 may be functioned, operated and operated by a computer to carry out this step. In step 152, the inclination angle θ's is calculated. When powering off the instruments 10, 12, the calculated last tilt angle θ _L is stored.

The instrument 10, 12 is turned off in the dormant or off state for some time. In step 154 the instruments 10 and 12 are turned on and started to operate. Mechanism (10, 12) in step 155 requires an angular velocity to the acceleration (α _m (t)) measured, and the measured acceleration (α _m (t)) to to provide the acceleration (α) in the equation 1 ( It operates to correct ω (t)). Step 156 calculates the restart accelerometer bias β ₀ from the inclination angle θ _L in Equation 1.

7B is a flowchart of an embodiment of a return-to-position correction method. The steps of the method may be stored in the fluid medium 200 in a computer-readable form that can be read by a computer to perform the steps. The instruments 10, 12 may also function, operate and operate as a computer to carry out this step. In step 202, a return-to-position trigger is received from the user and the instruments 10, 12 determine its location and first altitude H ₁ . In step 204, instruments 10 and 12 detect the movement. In step 206 the return loop altitude H _R is determined when the instrument 10, 12 determines that it has returned to the same two-dimensional horizontal position within a threshold of one to three meters within a predetermined time range. The length of time may be several seconds to several minutes. Alternatively, measure the return loop altitude H _R when the second trigger is received.

In a simple case, the driver issues a trigger to the instrument 10, 12 when the vehicle is parked and driven to the loop back to the same parking position. This method assumes that the return loop altitude H _R will be equal to the starting altitude H ₁ when the instrument 10, 12 returns to the same horizontal position or detects a second trigger. In step 208, instruments 10 and 12 determine an accelerometer bias β that causes the sum of altitude changes ΔH's to be zero, or the accelerometer such that the starting altitude H ₁ and the return loop altitude HR are equal. The bias β is determined.

7C is a plot of vehicle movement for return-to-position calibration. Vehicle 14 starts at position 250 and moves counterclockwise loop 252 to starting position 250 for single loop correction. The vehicle 14 returns back to the starting position 250 via the clockwise loop 254 for double loop correction. Either or both of loop 252 and loop 254 may be repeated many times and the averaged result and loop are not required to be exactly circular.

8 is a flow chart of double loop correction using a return-to-position method to determine values for setpoint β _I and linear position offset L and yaw alignment angle γ for accelerometer bias β. to be. The steps of the method may be stored in the fluid medium 300 in a computer-readable form that can be read by a computer to execute the steps. The instruments 10, 12 may function, operate and operate as a computer to carry out the steps. In step 304 the instruments 10, 12 are warmed up. Warming up stabilizes the accelerometer bias β. In step 306 the vehicle 14 parks toward the first direction. The first acceleration α _m (t) is measured. Since the vehicle 14 is not moving, this measured acceleration α _m (t) will be small.

In step 308 the vehicle 14 is slowly driven and stopped in the opposite direction to return to the same parking space. The second acceleration α _m (t) is measured. Since the vehicle 14 is not moving, this measured acceleration α _m (t) will be small. In step 314 the difference between the first and second measured accelerations α _m (t) is used to distinguish the effect of the acceleration of gravity g on the accelerometer bias β _I and the parking tilt angle of the ground 25. I use it.

In order to determine the starting altitude H ₁ at step 316, the instruments 10, 12 use the calculated accelerometer bias β _I and the preselected estimate of the position offset L and yaw alignment angle γ. In step 318 the vehicle 14 is driven rapidly in a clockwise (or counterclockwise) loop back into the parking space. It must be driven fast enough to cause a revolving speed (ω (t)) similar to the revolving speed (ω (t) 's) that will occur during operation. In step 322 a first return-to-position (RTP) altitude H _R1 is determined. In step 324 the vehicle 14 is quickly driven in the opposite loopback to the parking space. It must be driven fast enough to induce a yaw rate (ω (t)) similar to the yaw rate (ω (t) 's) that will occur during operation. In step 326 a second return-to-position (RTP) altitude H _R2 is determined. In step 328, the effective installation position offset L and yaw alignment angle (Equation 2 and 3) from the starting altitude H ₁ , the first RTP altitude H _R1 and the second RTP altitude H _R2 are calculate γ). Step 328 is such that the sum of altitude changes ΔH between the starting altitude H ₁ and the first RTP altitude H _R1 and between the first RTP altitude H _R1 and the second RTP altitude H _R2 is zero. The accelerometer bias β _I , the position offset L and the yaw alignment angle γ are determined to be: Or determine the accelerometer bias (β _I ), position offset (L) and yaw alignment angle (γ), where the starting altitude H ₁ , the first RTP altitude H _R1 and the second RTP altitude H _R2 are equal. do.

Determination of altitude and tilt angle

The following section shows the operation of the instruments 10, 12 for calculating the altitude change ΔH and the inclination angle θ. Equation 2 shows the calculation of the altitude change ΔH based on the corrected acceleration α _c (t) and velocity v (t) for the measurement time ΔT and the gravitational acceleration constant g.

Equation 2)

Equation 3 is measured acceleration (α _m (t)), accelerometer bias (β), position yaw rate error (ω ² (t) × L), and alignment yaw rate error (ω (t) × v (t) × the corrected acceleration α _c (t) as a function of γ).

3) α _c (t) = α _m (t) + β-ω ² (t) L-ω (t) v (t) γ

The position yaw rate error is the same for left turn or right turn. Alignment yaw rate error is the same and opposite for left turn and right turn. Equation 4 represents the inclination angle θ as a function of the corrected acceleration α _c (t) and the rate of change of velocity Δv / Δt over time.

4) θ = Sin- ¹ {[α _c (t))-Δv / Δt] / g}

General profit

Embodiments may improve the performance and optionally map-match performance of vehicle navigational mechanisms including GPS receivers, yaw rate gyro or heading gyro, transmission shafts or wheel speed measurement devices. To improve the accuracy of the instrument within one or two meters, without differential GPS measurement; And to provide continuous and smooth elevation and tilt angles without continuous or smooth GPS measurements, embodiments may add a forward linear accelerometer and some accelerometer correction algorithms.

It is known that GPS latitude and longitude measurements are associated with errors on altitude. By improving knowledge of altitude, this interrelationship may improve knowledge of latitude and longitude. In limited vision, the GPS speed may be noisy, or the geometry of the GPS satellite signal (DOP) may be poor, or only three GPS satellite signals may be valid. In such cases, improved altitude measurements significantly improve latitude and longitude measurements.

Highly direct knowledge, which may be superior to GPS accuracy, is used in combination with a map-matching database containing altitude information. Using accurate altitude or elevation change information, the map-match algorithm determines whether the vehicle is on one of two parallel tracks on a highway-off ramp, whether one is rising or falling, You can quickly decide whether or not. With GPS and directional gyro alone, the two possible paths are horizontally separated from the map-match database by a distance appropriate for GPS accuracy, and may not be able to generate the accuracy needed to make such a decision until the actual distance is traveled. . Knowledge of whether the vehicle has left the highway is important for quickly determining route information. Elevated direct knowledge may also set the vehicle's vertical position when in a multi-tiered parking structure without GPS coverage or incorrect GPS-based altitude.

9A shows a parking lot in which the DR altitude H is used to distinguish between floors 512 connected by a spiraling ramp when the floor 512 is not reliably distinguished by GNSS-based altitude. Layer 512 is shown.

FIG. 9B shows the highway 522, the upward access road ramp 524 and the downward access road ramp 526 and through the measurement of the inclination angle θ when the ramp road is not reliably distinguished by the GNSS-based direction. The upward ramp road 524 and the downward ramp road 526 are distinguished.

Although the invention has been described in terms of embodiments, it will be understood that such disclosure is not to be construed as limiting. There is no doubt that various supersets, subsets, and equivalents will be apparent to those skilled in the art after reading this disclosure. However, these supersets, subsets and equivalents should not be considered as limiting the idea of the invention. Accordingly, the following claims will be construed to cover the true spirit and scope of the present invention.

concept

Concept 1. Speedometer to determine forward speed;

An accelerometer for measuring forward acceleration; And

And a DR altitude calculator that calculates an altitude change based on the speed and the measured acceleration.

Concept 2. yaw rate sensor for measuring yaw rate; And

And a yaw correction device for correcting the measured acceleration according to the yaw rate to determine the corrected acceleration.

And the DR altitude calculator is configured to use the corrected acceleration along with the velocity to calculate the altitude change.

Concept 3. The yaw correction device of claim 2, wherein the yaw correction device includes a yaw position corrector for correcting the yaw rate to the measured acceleration at a linear position offset in each rotation radius to determine the corrected acceleration.

Concept 4. Measuring the linear position offset using a dual return loop having a first return-to-position after one loop, either a clockwise loop or a counterclockwise loop, and a second return-to-position after the loop opposite to the direction. The altimeter of concept 3 further comprising a return-to-position correction detector.

Concept 5. The altimeter of Concept 2 wherein the yaw correction device includes a yaw alignment corrector configured to correct the yaw rate to a measured acceleration at a yaw alignment angle to determine the corrected acceleration.

Concept 6. Measuring the linear position offset using a dual return loop having a first return-to-position after one loop, either a clockwise loop or a counterclockwise loop, and a second return-to-position after the loop opposite to the direction. The altimeter of concept 5 further comprising a return-to-position correction detector.

Concept 7. The apparatus further includes a bias compensator for correcting the measured acceleration according to the accelerometer bias to determine the corrected acceleration.

And the DR altitude calculator is configured to use the corrected acceleration along with the velocity to calculate the altitude change.

Concept 8. The altimeter of Concept 7 further comprising a Kalman filter configured to filter the elevation change with an external altitude fix to measure the accelerometer bias.

Concept 9. The altimeter of Concept 8 wherein the external altitude fix is derived from a GNSS signal.

Concept 10. The altimeter of Concept 8 wherein the external altitude fix is derived from map-matching.

Concept 11. The altimeter of concept 7 further comprising a return-to-position corrector for measuring the accelerometer bias based on a return-to-position.

Concept 12. The altimeter of concept 7 further comprising a return-to-position corrector for measuring the accelerometer bias based on a return-to-position facing in the opposite direction.

Concept 13. An inclination angle calculator for calculating an inclination angle based on the corrected acceleration and the speed change rate; And

And a restart bias detector that measures the accelerometer bias in the restart movement after the pause time period based on the last angle of inclination before the pause time period.

Concept 14. GNSS receiver for determining GNSS-based location including GNSS-based altitude; And

Further comprising a yaw rate sensor for measuring the yaw rate,

And the DR altitude calculator is configured to use the yaw rate, the GNSS-based position and the altitude change to provide a DR altitude with improved accuracy than the GNSS-based altitude.

Concept 15. It further includes a map having a floor of parking lot,

And said DR elevation is used to distinguish between said layers when said layers cannot be reliably distinguished by said GNSS-based altitude.

Concept 16. Determining forward speed;

Measuring forward acceleration; And

Calculating an altitude change based on the speed and the measured acceleration.

Concept 17. Measuring the yaw rate; And

Correcting the measured acceleration according to the yaw rate to determine a corrected acceleration;

Computing the elevation change includes using the corrected acceleration with the velocity to calculate the elevation change.

Concept 18. The method of concept 17 wherein correcting the measured acceleration in accordance with the yaw rate includes correcting the yaw rate with linear position offsets respectively in the radius of rotation to determine the corrected acceleration.

Concept 19. The linear position offset comprising using a dual return loop having a first return-to-position after one of the clockwise or counterclockwise loops and a second return-to-position after the loop opposite to the direction The method of concept 18 further comprising measuring.

Concept 20. The method of concept 17 wherein correcting the measured acceleration according to the yaw rate comprises correcting the yaw alignment angle to the yaw rate to determine the corrected acceleration.

Concept 21. The yaw alignment angle comprising using a dual return loop having a first return-to-position after one of the clockwise or counterclockwise loops and a second return-to-position after the loop opposite to the direction The method of concept 20 further comprising measuring.

Concept 22. further comprising correcting the measured acceleration according to the accelerometer bias to provide a corrected angular velocity,

Computing the elevation change includes using the corrected acceleration with the velocity to calculate the elevation change.

Concept 23. The method of concept 22 further comprising Kalman filtering the elevation change with an external altitude fix to measure the accelerometer bias.

Concept 24. The method of concept 23 wherein the external elevation fix is derived from a GNSS signal.

Concept 25. The method of concept 23 wherein the external elevation fix is derived from map-matching.

Concept 26. The method of concept 22 further comprising measuring the accelerometer bias based on a return-to-position.

Concept 27. The method of concept 22 further comprising measuring the accelerometer bias based on a return-to-position facing in the opposite direction.

Concept 28. calculating an inclination angle based on the corrected acceleration and the rate of change of speed; And

Measuring the accelerometer bias in the reactivation movement after the pause time period based on the last angle of inclination before the pause time period.

Concept 29. Determining GNSS-based location including GNSS-based altitude; And

Measuring the yaw rate;

And calculating the DR altitude comprises using the yaw rate, the GNSS-based position and the altitude change to provide a DR altitude with an improved accuracy than the GNSS-based altitude.

Concept 30. providing an electronic map having a floor of a parking lot; And

And using the DR altitude to distinguish between the layers when the layer cannot be reliably distinguished by the GNSS-based altitude.

1 shows a vehicle including a dead reckoning altimeter and inclinometer;

FIG. 1A shows the yaw alignment angle for the accelerometer of the dead reckoning altimeter and inclinometer of FIG. 1;

2 is a block diagram of the dead reckoning altimeter and inclinometer of FIG. 1;

3 is a block diagram of an acceleration correction device of the dead reckoning altimeter and inclinometer of FIG. 1;

4 is a block diagram of the dead reckoning altimeter and inclinometer of FIG. 1 including a Kalman Filter to improve the accuracy of three-dimensional position, velocity and heading;

5 shows the accelerometer position offset and yaw alignment angle for the dead reckoning altimeter and inclinometer of FIG. 1;

6 is a flow chart of a method for determining altitude change and tilt angle and dead reckoning position, velocity and heading;

7A is a flowchart of a method of determining accelerometer bias calibration for restarting;

FIG. 7B is a flowchart of a return-to-position method for determining accelerometer bias calibration; FIG.

FIG. 7C is a diagram showing vehicle movement in which a counter rotation loop is used to determine accelerometer bias calibration for the dead reckoning altimeter and inclinometer of FIG. 1; FIG.

8 is an illustration of the return-to-position initial installation method for determining the accelerometer bias, linear position offset and yaw alignment angle for the dead reckoning altimeter and inclinometer of FIG. 1 and the method of FIG. It is a flowchart;

9A and 9B illustrate the floor and highway connecting ramp roads of a parking lot in which the dead reckoning altimeter and / or inclinometer of FIG. 1 is advantageously used.

Claims (30)

A speedometer for determining the forward speed; An accelerometer for measuring forward acceleration; And And a DR altitude calculator that calculates an altitude change based on the speed and the measured acceleration. The method of claim 1, Yaw rate sensor for measuring the yaw rate; And And a yaw correction device for correcting the measured acceleration according to the yaw rate to determine the corrected acceleration. And the DR altitude calculator is configured to use the corrected acceleration along with the velocity to calculate the altitude change. The method of claim 2, And the yaw correction device includes a yaw position corrector for correcting the yaw rate to the measured acceleration at a linear position offset in a rotation radius, respectively, to determine the corrected acceleration. The method of claim 3, Return-measure the linear position offset using a dual return loop having a first return-to-position after one loop, either a clockwise loop or a counterclockwise loop, and a second return-to-position after the loop opposite to the direction. A dead reckoning altimeter, further comprising a two-position correction detector. The method of claim 2, And the yaw correction device includes a yaw alignment correcting device configured to correct the yaw rate to the measured acceleration at the yaw alignment angle to determine the corrected acceleration. The method of claim 5, Return-measure the linear position offset using a dual return loop having a first return-to-position after one loop, either a clockwise loop or a counterclockwise loop, and a second return-to-position after the loop opposite to the direction. A dead reckoning altimeter, further comprising a two-position correction detector. The method of claim 1, And a bias correction device for correcting the measured acceleration according to the accelerometer bias to determine a corrected acceleration, And the DR altitude calculator is configured to use the corrected acceleration along with the velocity to calculate the altitude change. The method of claim 7, wherein And a Kalman filter configured to filter the change of altitude with an external altitude fix to measure the accelerometer bias. The method of claim 8, The external altitude fix is a dead reckoning altimeter derived from a GNSS signal. The method of claim 8, The external altitude fix is a dead reckoning altimeter derived from map-matching. The method of claim 7, wherein And a return-to-position corrector for measuring the accelerometer bias based on a return-to-position. The method of claim 7, wherein And a return-to-position corrector for measuring the accelerometer bias based on a return-to-position in an opposite direction. The method of claim 7, wherein An inclination angle calculator for calculating an inclination angle based on the corrected acceleration and the speed change rate; And And a restart bias detector that measures the accelerometer bias in the restart movement after the pause time period based on the last angle of inclination before the pause time period. The method of claim 1, A GNSS receiver for determining a GNSS-based location including a GNSS-based altitude; And Further comprising a yaw rate sensor for measuring the yaw rate, And the DR altitude calculator is configured to use the yaw rate, the GNSS-based position and the altitude change to provide a DR altitude with improved accuracy than the GNSS-based altitude. The method of claim 14, It further includes a map having a floor of the parking lot, The DR altitude is used to distinguish between the layers when the layers cannot be reliably distinguished by the GNSS-based altitude. Determining the rate of advancement; Measuring forward acceleration; And Calculating an altitude change based on the speed and the measured acceleration. The method of claim 16, Measuring the yaw rate; And Correcting the measured acceleration according to the yaw rate to determine a corrected acceleration; Calculating the altitude change includes using the corrected acceleration with the speed to calculate the altitude change. The method of claim 17, Correcting the measured acceleration in accordance with the yaw rate comprises correcting the yaw rate with linear position offsets respectively in a rotational radius to determine the corrected acceleration. The method of claim 18, Measuring the linear position offset comprising using a dual return loop having a first return-to-position after one loop, either a clockwise loop or a counterclockwise loop, and a second return-to-position after the loop opposite to the direction How to include more. The method of claim 17, Correcting the measured acceleration according to the yaw rate comprises correcting the yaw alignment angle to the yaw rate to determine the corrected acceleration. The method of claim 20, Measuring the yaw alignment angle comprising using a dual return loop having a first return-to-position after one of the clockwise or counterclockwise loops and a second return-to-position after the loop opposite to the direction How to include more. The method of claim 16, Further correcting the measured acceleration according to the accelerometer bias to provide a corrected angular velocity, Calculating the altitude change includes using the corrected acceleration with the speed to calculate the altitude change. The method of claim 22, And Kalman filtering the elevation change with an external altitude fix to measure the accelerometer bias. The method of claim 23, wherein The external altitude fix is derived from a GNSS signal. The method of claim 23, wherein Wherein the external altitude fix is derived from map-matching. The method of claim 22, Measuring the accelerometer bias based on a return-to-position. The method of claim 22, And measuring the accelerometer bias based on a return-to-position facing in the opposite direction. The method of claim 22, Calculating an inclination angle based on the corrected acceleration and the rate of change of speed; And Measuring the accelerometer bias in the restart movement after the stop time period based on the last angle of inclination before the stop time period. The method of claim 16, Determining a GNSS-based location, including a GNSS-based altitude; And Measuring the yaw rate; Computing the DR altitude includes using the yaw rate, the GNSS-based position and the altitude change to provide a DR altitude with improved accuracy than the GNSS-based altitude. The method of claim 29, Providing an electronic map having a floor of a parking lot; And Using the DR altitude to distinguish between the layers when the layer cannot be reliably distinguished by the GNSS-based altitude.

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